Hi everyone,
I have a study power question. I cannot get my head around the whole concept.
I want to use the STATA sampsi command to calculate the power of my study.
Here are my details:
My outcome of interest: Stillbirth (observed stillbirth rate 0.38%)
My entire sample size (cohort) is:n= 832,626
My exposed group are women with a prior Caesarean section (n=145,864)
My comparison group are women with a prior vaginal delivery (n=686,762)
The proportion of women with a stillbirth in the exposed (Caesarean) group is 579/145,864 = 0.40
The proportion of women with a stillbirth in the unexposed (vaginal group) is 2569/686,762 = 0.37
The Caesarean section rate in the cohort is 17.54%
How do I use this information to calculate the power at 0.05 significance (two-sided) [assuming this is the right thing to do]?
Thanking you!
By the way, I am looking to see if a prior Caesarean section increases the risk of subsequent stillbirth
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